Traditional methods of digital communication rely on certain mathematical functions, which can be hacked with the right tools and know-how. Quantum communications, however, send information embedded in entangled particles of light, in this instance by a satellite named Micius, in a process which is said to be completely unhackable. It's so secure that anyone even attempting to infiltrate the communication without authorization will be uncovered. As Johannes Handsteiner from the Austrian Academy of Sciences explained, "If somebody attempts to intercept the photons exchanged between the satellite and the ground station and to measure their polarization, the quantum state of the photons will be changed by this measurement attempt, immediately exposing the hackers."
Of course, it's not impossible that someone could find a way to hack this kind of communication at some point in the future, but right now it represents the most secure way of sharing digital data yet. According to the Chinese Academy there are plans to carry out similar test conversations between China and Singapore, Italy, Germany and Russia. And if Russia is involved, it won't be long before the US gets in on the technology as well.